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Chapter 6 Advanced Topics 83
Fast and Safe Speed Modes
The WinSpec/32 Experiment Setup Timing tab page allows the user to choose Fast or
Safe Mode. Figure 40 is a flowchart comparing the two modes. In Fast Mode operation,
the MicroMAX runs according to the tim
ing of the experiment, with no interruptions from
the computer. In Safe Mode operation, the computer processes each frame as it is received.
The MicroMAX cannot collect the next frame until the previous frame has been completely
processed.
Fast Mode operation is primarily for collecting "real-time" sequences of experimental
data, where tim
ing is critical and events cannot be missed. Once the MicroMAX is sent
the Start Acquisition command by the computer, all frames are collected without further
intervention from the computer. The advantage of this timing mode is that timing is
controlled completely through hardware. A drawback to this mode is that the computer
will only display frames when it is not performing other tasks. Image display has a lower
priority, so the image on the screen may lag several images behind. A video monitor
connected to the VIDEO output will always display the current image. A second
drawback is that a data overrun may occur if the number of images collected exceeds the
amount of allocated RAM or if the computer cannot keep up with the data rate.
Safe Mode operation is primarily useful for experim
ent setup, including alignment and
focusing, when it is necessary to have the most current image displayed on the screen. It
is also useful when data collection must be coordinated with external devices such as
external shutters and filter wheels. As seen in
Figure 40, in Safe Mode operation, the
com
puter controls when each frame is taken. After each frame is received, the camera
sends the Stop Acquisition command to the camera, instructing it to stop acquisition.
Once that frame is completely processed and displayed, another Start Acquisition
command is sent from the computer to the camera, allowing it to take the next frame.
Display is therefore, at most, only one frame behind the actual data collection.
One disadvantage of the Safe mode is that events m
ay be missed during the experiment,
since the MicroMAX is disabled for a short time after each frame.